1. Field of the Invention
The present invention relates to an antenna and, more particularly, to an antenna having multiple band and broad band characteristics by being provided with a capacitive element.
2. Related Art Technology
Generally, as an antenna becomes more compact in size, various problems may occur, such as radiation efficiency of the antenna being degraded, bandwidth becoming narrower, and antenna gain being reduced. However, as mobile telecommunications devices are being more developed and evolved, the necessity of high-performance antenna being more compact in size and having a wider bandwidth is also growing accordingly.
In earlier mobile telecommunications device, either a ¼ wavelength monopole antenna was used as an internal antenna, or a helical external antenna was mainly used. However, such antennae cause an inconvenience in portability for the users and are also disadvantageous in radiation efficiency and robustness.
In order to resolve such shortcomings, active research was carried out on internal antennae and, most particularly, research was carried out most vigorously on inverse-F antennae. The inverse-F antenna is fabricated by simple fabrication process and is configured to have a flat surface structure, thereby being easily applied as an internal antenna. Accordingly, the inverse-F antenna is now most widely used as the internal antenna of the current mobile telecommunications devices.
FIG. 1 illustrates a structure of a related art inverse-F antenna. Referring to FIG. 1, the related art inverse-F antenna includes a radiator (100), a ground plane (102), a ground pin (104), and a feeding pin (106).
The radiator (100) is generally configured to have the form of a flat plate. Herein, the radiator (100) maintains a predetermined distance from the ground plane, and has a function of transmitting and receiving RF signals. Also, the feeding pin (106) is electrically connected to a feeding line, and a signal is fed to the radiator (100) through the feeding pin (106).
When using the above-described related art antenna, the antenna is operated as an antenna having a single band, thereby having the problem of not being capable to have the characteristics of a broad band.